What would case a code PO420 and how would I fix.

THIS IS THE SITE I LIKEHERE'S AN EXAMPLE ON HOW TO USE ITREMOVE THE "P0420" AND INSERT THE CODES YOU COME UP WITH, ONE AT A TIME

https://www.2carpros.com/trouble_codes/obd2 (CODE IS "P"---ZERO--FOUR--TWO---ZERO)

I USUALLY COMPILE INFO FROM SEVERAL SOURCES THEN COME UP WITH A BATTLE PLAN....GENERALLY THE CHEAPEST WAY OUT TRIED 1ST...FROM MY MOST RELIABLE SOURCES

IMMA JEEP CJ GUY AND RESPOND BETTER TO THEM, IF I AM UNABLE TO OFFER ADVICE, I WILL LOCATE ANOTHER FELLER HERE THAT MAY BE MORE EXPERIENCED WITH YOUR VEHICLE----MANY WILL JUMP IN ON THEIR OWN TO HELP WITHOUT ME LOOKING FOR THEM

DEPENDING ON THE PROBLEM THIS COULD BE SOMETHING SIMPLE AND A EZ DIY REPAIR......HOPEFULLY IT WILL BE AN INEXPENSIVE FIX

SOMETHING LIKE THIS MIGHT AID YOU ALSO, I SWEAR BY 'EM

https://www.2carpros.com/questions/2007-ford-taurus-tune-up

KEEP US POSTED....I HOPE THIS HELPED!

THE MEDIC